Detection Using Bioassays

It is important to note that pollutants rarely affect a single factor or parameter. To that effect, chemical-based criteria by themselves cannot sufficiently predict the 

TABLE 2.1 Comparison of Concentrations of Various Pharmaceutical Compounds Using ELISA and LC-MS or GC-MS-MS 

Compound Matrix Concentration LC MS or ELISA GC MS MS % Difference Reference  

17 (3-estradiol (E2 ng/L) WWTP A (secondary effluent activated sludge and chlorine disinfection) 3.68 3.9 0 Huang and Sedlak (2001) 

Immunochemical approaches are cheaper, readily adaptable, rapid, portable, and reduce the need for expensive analytical equipment. They can also be used to simultaneously assay a large number of samples over a short period of time. One of the major factors that still hmits the use of this technique in the detection of a wider range of PPCPs in the environment is the lack of suitable antibodies sensitive to most PPCPs that occur in the environment. Furthermore, immunoassay accuracy can be susceptible to cross reactions and other effects from the matrix, giving false positives in some instances (Huang and Sedlak, 2001). Thus, it is recommended that immunoassay analytical results be validated with GC- or LC-based methods. 

---

Nishioka MG, CC Howard, DA Conros, LM Ball (1988) Detection of hydroxylated nitro aromatic and hydroxy-lated nitro polycyclic aromatic compounds in ambient air particulate extract using bioassay-directed fractionation. Environ Sci Technol 22 908-915. 

Nishioka, M. G., C. C. Howard, D. A. Contos, L. M. Ball, and J. Lewtas, Detection of Hydroxylated Nitro Aromatic and Hy-droxylated Nitro Polycyclic Aromatic Compounds in an Ambient Air Particulate Extract Using Bioassay-Directed Fractionation, Environ. Sci. Technol., 22, 908-915 (1988). 

Endotoxicity results from the interaction of a bacterial cell envelope component (e.g., LPS or PG with a cell surface receptor constituting part of the nonspecific immune system, (i.e., a toll-like receptor on white blood cells). This results in the production of cytokines [e.g., interleukin 1 (IL-1) or tumor necrosis factor (TNF)] as part of an intracellular enzyme cascade which can cause severe tissue injury. Bioassays or immunoassays can be used to detect such reactions respectively. As noted above the most widely used bioassay is the LAL assay. A lysate of amoebo-cytes of the horseshoe crab (Limulus) contains an enzymatic clotting cascade which is activated by extremely low levels of LPS (nanogram levels or lower). There are variants of this assay that can detect PG, but they are not as widely used. As noted above, other bioassays employ cultured cell lines that respond to LPS or PG, respectively. Unfortunately bioassays are highly amenable to false positives (from the presence of cross-reactive substances) or false negatives from inhibition (by contaminants present in the sample) [10]. A detailed discussion of these assays is beyond the scope of this chapter and has been reviewed elsewhere [1]. 

A previous exploratory study attempted to recover the soluble, poorly volatile subclass of organic compounds in water (3). It used a set.of sequential adsorbents. Silica gel, the first adsorbent, filtered out particulate matter and adsorbed some hydrophobic compounds. The next adsorbent was a cation-exchange bed that recovered cations and amphoteric substances, and the last adsorbent was an anion-exchange bed. The effluent from this series of adsorbents contained the neutral compounds. The eluates from each bed and the effluents were then concentrated under vacuum. This system, the parfait method, was demonstrated to recover parts-per-billion concentrations of several known mutagens in amounts sufficient to be detected by bioassay. 

There are several approaches to detecting esterases, each with different degrees of feasibility, practicality and costs. The conventional approach of using bioassay to determine the complete dose-response relationship of a... 

The C5(6) desaturase is a membrane bound enzyme localized in the endoplasmic reticulum, and for the first time, we have developped an enzymatic bioassay. The enzymatic A -sterol fomied was detected using its typical UV absorbance at 281,5 nm. The properties of the microsomal system have been studied and the kinetics of the desaturation reaction has been established [1]. 

Fascinating plant folklore and ethnopharmacology leads to medicinal potential. Examples are the muscle relaxants based on the arrow poison, curare, from species of Chondrodendron, and the antimalarials derived from species of Cinchona and Artemisia. The methods of detection of pharmacological activity have become increasingly reliable and specific, frequently involving enzymes in bioassays and avoiding the use of laboratory animals. By using bioassay linked fractionation of crude plant juices or extracts, compounds can be specifically... 

Step 4 Compost analysis for conventional parameters determining any quality change compared with the blind and ecotoxicity test using at least two plant species if negative influences are detected additional bioassays should be performed using more plant species, daphnia, water lens, luminescent bacteria or special local species. 

---